Rule

Rule is a tiny robot that is programmed to act as a game referee for Hiiragi Academy's main campus.

Bio
An artificial-intelligence that acts as the referee for the rank matches between students. In addition, it acts as the referee for Junichirou's games during the SS group war.

Chapter Appearances
83, 84, 85, 86, 87, 90, 91, 92, 96, 100